Phylogenetic relationships and evolutionary history of the southern hemisphere genus Leptinella Cass. (Compositae, Anthemideae)

• Main Author: Himmelreich, Sven
• Format: Thesis
• Language: English
• Published: 2011
• Subjects: 580 Pflanzen (Botanik); ddc:580; Antarctic; New Zealand; Antarc*
• Online Access: https://epub.uni-regensburg.de/16970/; https://epub.uni-regensburg.de/16970/1/Himmelreich.pdf

The genus Leptinella Cass. (Compositae, Anthemideae) is widely distributed in the southern hemisphere (Australia, Chatham Islands, New Guinea, New Zealand, South America, sub-Antarctic Islands). Leptinella comprises 42 taxa and consists of small perennial and predominantly procumbent herbs. The genus is characterised by a remarkable variety in sex expression: there are populations with monoecious, paradioecious, and dioecious plants. Additionally, Leptinella forms an impressive polyploid complex with chromosome numbers ranging from tetraploid to a chromosome set of 2n = 24x. In the present thesis, different molecular methods are used to reconstruct the phylogenies of the genus Leptinella and related genera. The obtained molecular phylogenies are then used to a) investigate the intergeneric and infrageneric relationships of Leptinella, b) elucidate the origin, the biogeography and the divergence time of the genus, and c) reconstruct the evolution of polyploidy and sex expression in Leptinella. Chapter 2 deals with the intergeneric relationships of Leptinella. One region from the nuclear (ITS) and the chloroplast genome (ndhF) were chosen for amplification and sequencing to reconstruct the molecular phylogeny of the southern hemisphere members of the tribe Anthemideae. The analyses show that the subtribes sensu Bremer and Humphries (1993) are polyphyletic. As a consequence of the non-monophyletic nature of these subtribes, an alternative generic grouping of the southern hemisphere Anthemideae is discussed (Osmitopsis, Cotula-group, Athanasia-grade, Pentzia-clade). The study shows that the genus Leptinella is a member of the basal Cotula-group which also contains seven southern African genera, the South American genus Soliva, and the widespread southern hemisphere genus Cotula. Chapter 3 and 4 deal with the infrageneric phylogeny of the genus Leptinella. For this purpose two different methods were used: DNA sequencing and AFLP fingerprinting. Both methods are suitable for the determination of taxon groups within ...